The buffalo fence is 3000km long and was erected in 1954 to segregate wild buffalo herds from domestic free-range cattle. It was built to prevent the spread of foot and mouth desease. The problem is that the fence prevents wild animals from migrating to water sources along age-old seasonal routes. As a result Botswanas wildebeest population declined by 99% over the past decade and all buffalo and zebra are stranded north of the fence.